As display devices which are used for a monitor of a computer, a television, or a cellular phone, there are an electroluminescent display device which is a self-emitting device and a liquid crystal display device (LCD) which requires a separate light source.
An applicable range of the display device is diversified to personal digital assistants as well as monitors of computers and televisions and a display device with a large display area and a reduced volume and weight is being studied.
Further, recently, a foldable display device which forms a display unit and wiring lines on a flexible substrate to be freely folded or unfolded is attracting an attention as a next generation display device.